Orthopaedic implants, such as the interlocking nail, have significantly widened the scope for intramedullary (IM) fixation of bone fractures. Anchoring an IM nail to a bone makes the construct more stable longitudinally and stops rotation of the nail within the bone. A typical IM nail fixation surgery involves a combination of jigs, x-ray imaging, and manual “eye-balling” to locate and drill the distal screw holes and to install the screws in the screw holes.
In IM nail fixation surgery, an IM nail is inserted into the canal of a fractured long bone in order to fixate the fractured ends together. Typically, the proximal locking is performed first and is usually carried out with a jig. Nail deformation during intramedullary insertion and manufacturing capabilities, however, may make a jig inaccurate for the distal screws. In fact, the positioning of the distal locking screws and alignment of the drill for the drilling of the distal screw holes is the most time consuming and challenging step of the implantation procedure. The two main reasons for failure in distal locking are (1) incorrect entry point on the bone and (2) wrong orientation/trajectory of the drill. If either of these problems occurs, then the drill will not go through the nail hole.
An inaccurate entry point also compounds the problem as the rounded end of the drill bit often slips, damaging healthy bone rendering it difficult to place another drill hole next to the inaccurate hole. Inaccurate distal locking may lead to premature failure with breakage of the nail through the nail hole, breakage of the screw, or the breaking of the drill bit within the bone.
In order to overcome the problems associated with distal locking, instrumented IM nails have been designed for distal locking. The instrumented IM nails include a probe having one or more sensors connected to one or more processors. Calibration of the IM nail is carried out to insure that the spatial relationship between the one or more magnetic sensors and one or more landmarks, such as screw holes on the IM nail, are known and accurate. Once calibrated, the IM nail is packaged for use, and the sensor(s) must maintain their position and orientation relative to the landmarks in order for the IM nail to be properly secured within the body of a patient. Limiting or preventing movement of the probe and the associated sensor(s) relative to the IM nail and/or the landmark(s) following calibration and packaging, and prior to use, has been a challenge.
Using adhesives to glue the probe and associated sensor(s) to the IM nail, and in particular, to a groove formed in the IM nail, have been an accepted technique for preventing movement of the probe and sensor(s) relative to the IM nail and landmark(s). Use of adhesives, however, have made it very difficult, and in most cases, impossible, to remove the probe, associated sensor(s), and adhesive following surgery. This has led to increased inventory and parts costs and has prohibited reuse of costly materials.
There remains a need for a solution that provides features or structures to the IM nail, and in particular, a groove formed in the IM nail, that sufficiently capture the probe and associated sensor(s) following calibration of the IM nail. Further, a need exists for insuring that the position and orientation of the sensor(s) relative to the landmark(s) on the IM nail remain set for targeting and locking of the IM nail within the body, and for providing for easy removal of the probe and associated sensor(s) after targeting and/or locking of the IM nail so that the probe and sensor(s) may be cleaned and reused again. Moreover, a need exists for an implant that includes a probe and associated sensor captured in a manner that permits targeting and locking of a driving end of the implant prior to fixation of the non-driving end.